Intercommunicating telephone system.



'G- DEAKIN.

INTERCOMMUNICATING TELEPHONE SYSTEM.

APPLICATION FILED AUG. I2. 1909.

1 1 59 1 88, Patented Nov. 2, 1915.

3 SHEETSSHEET I- Z''zwessess I Izzy/ 222921 Gem/d fieawz By flifys.

COLUMBIA PLAN c.

G. DEAKIN.

INTERCOMMUNIQATING TELEPHONE SYSTEM. APPLICATION FILED AUG. I2, 19 09.

1,159,188, I PatentedNov. 2, 1915.

3 SHEETS-SHEET 2- ZZ/z'Znesses: [72 76721 07":

Gem/d flea/rm G. DEAKIN. INTERCOMMUNICATING TELEPHONE SYSTEM. APPLIQATION F |LED AUG. 12, 1909.

1,159,188; Patented Nov. 2, 1915.

3 SHEETS-SHEET 3- Zflzizzesjej fiz eflfar. GemZdJea/rm CDLUIIBIA PLANOGRAPH IO-,WASHINGTON D c the trunk, this being necessary by the gen- MCMEEN AND KEMIPSTER B. MILLER;

VGERALIJTDEAKIN, or OAKLAND, CALIFORNIA, ASSIGNOR'OF ONE- ALF r0 M nama MILLER, or CHICAGO, ILLINOIS, A COPARTNERSI-IIP COMPOSED or SAMUEL e.

INTERCOMIVIUNICATING TELEPHONE SYSTEM.

' To all whom it may concern Be it known that I, GERALD DEAKIN, a]

citizenof the United States ofAmerica, and a resident of Oakland, county of Alameda,

lowing is a specification.

My invention pertains; to intercommunicating private branch exchange systems.

Specifically it is shown pertaining to such systems used in connection with automatic central ofiices and connectedwith the central Jthe beginnmg of conversation.

office by a trunk or a series of trunks.

By intercommunicatingexchange is meant an exchange at Which each: subscriber ,has

direct access to all the telephone .lines of the exchange and operates a switching de- I vice at flhis station to connect his telephone set with any desired one of the lines. When such an'exchange includes as one of its llnes the conductors of a trunk leading to a public service exchange, the intercommunicating system becomes a branchfexchange of the interruptionof a conversation by any second station of the branch exchange Which might attempt to forward a call over a busy trunk.

My invention has for its object the provision of equipment and a system of operationby Which a busy trunk circuit may be guarded at the private, branch exchange from all interruption by other stations which may attempt to forward a call. overthat trunk. o

In the system of my invention I provide Y also equipment such that, on an attempted outgoing call from an intercommumcatlng ,private branch station upon the trunk already being used on an outgoingconnection, the calling subscriber Will not be permitted to connect his telephone set to the trunk conductors,and furthermore his ringing buzzer Will be operated, thereby indicating to him audibly that the trunk with which connection is attempted is busy.- If, however, the trunkis busy on an incoming, call, a second station under some circumstances Will be permitted to come in upon Specification of Letters Patent. 'LPat e ted NOV. 2 1915' Applicationfiled August 12, 1909. Serial No. 512,526.

. eral plan of operating 'private branch'jexchanges, whereby all calls incoming are ansWered by an attendant at a predetermined station and the identity of the person'desired for conversation is ascertained, that person then being notified by any available means and then connecting himself 'to theitrunk" lineto respond'to the incoming calL This requires that on an incoming call a second station maybe permltted to connect its tele- I 1 phone set to the trunk While the first station,,'

or attendants station, still is upon the trunk' f for the purposeof supervising the call until party is obtained With an incoming call, he

may arbitrarily place the; guarding condi terrup't the conversation. In this classof private exchange it is cus tomary" at times for the attendant at the callreceivin g station to disconnectfhisi telephone taining the stationdesired and then to notify the desired station over one of the local in,-

"tion uponth'efltrunk, preventing. access of other statlons Who might inadvertently infrom the trunk after answering and ascertercomm'unicating lines. "In such practice,

during the interval between the release of:

the trunk atf thereceiving station and the picking up ofthe'trunk .at the desired station the trunk line to the central oflice .Will be open W th possible consequent undesirable operation of the central oifice relays, signals 3 or other apparatus designed "to. be con trolled by the I called subscribers bridge This operation in the case of a manualexchange is very objectionable and might be.

equally so in automaticlexchanges, Ipro- Which time the bridge at the receiving sta tion is removed automatically and thetrunkij is left under' full control of, the desired sta-i:

tion. 7

I provide further automatic,. signaling means whereby. any local station inattemp't 7 ing to call-any other local station" is notified in case the station called is .alrea'dy'in use,- I

This differentiates from, s the ordinary busy test by providing for a signalwhichbecomes active dependently" upon the busy; or idle condition of the telephoneqof the station the receiving station differs from the other rather than upon the busy or idle condition of. the line over which that station may be called. Thus, if station A calls station B, A will use Bs line, in so doing leaving As line idle although As station is busy on B s line. Station C desiring to call station B will receive the busy test as ordinarily pro vided.- Station G desiring to call station A would not receive a busy test as ordinarily provided because the line to station A is not busy and station O might ring indefinitely upon station A, annoying the person at that station by a ringing upon his bell to which he is unable to respond. In my im-.

" proved system, I provide a signal whereby station C is notified that station A is busy, and the telephone user at station C then may conduct himself accordingly.

In the drawings which accompany and form a part of this specification, Fig. 1 shows circuits of the private branch exchange system comprising three local lines and one trunk line. Fig. 2 shows the substation circuits of a station other'than the receiving station, and Fig. 3 shows the substation circuits of the receiving station;

stations in that it is called upon to perform different functions. v

The central oflice circuits are not shown, as it is thought that the system may be understood completely without confusing the V drawings by the addition of matter related only indirectly to the subject matter of my invention.

The keys of Fig. 1 are locking keys and preferably are of the mutually locking type in which the depression of any key results not only in the locking of that key in its depressed position, but also in the unlocking and consequent restoration of any other key which may have been locked in its depressed position at that time. In addition to the switching contacts whereby the substation telephone may be connected to the selected line, each key is provided with additional contacts for the signaling and guarding features of my invention.

Referring to key 3", the contacts 8 and 3 are adapted to connect the telephone set to the line eXtendingto station Z, and the contact 8 is a ringingcontact operated to connect with the line extending to station Z only when the key 3 is fully depressed, and key 8 then returning to an intermediate position in which 3 is open and 3 3 are closed, that being the locking position of depression of the key.

The substation equipments of Figs. 2 and 3 are of the type used by the Automatic Electric Company and are described in United States Patent No. 866,639, September 24, 1907, to E. D. Fales, to which a few additional switching springs have been added, the operation of which will be understood readily. Fig. 2 represents the substation equipment of a station such as Z, Y, etc., and is considered to be connected to the correspondingly lettered terminals of a station as Z, Fig. 1. Fig. 3 represents an attendants equipment or receiving station such as X and is considered to be connected to the correspondingly lettered terminals as shown at X, Fig. 1.

Upon an outgoing call from the private branch exchange, the patron, say at station Y, depresses his trunk key YT Fig. 1 and forwards the call by operating his dial Fig. 2, the signaling currents finding direct conducting path through the contacts of the relay 9, the bridge of the ringer 10 being opened by the condenser 11, to the right as viewed in Fig. 1 along the heavy lines to the central oiiice apparatus.

The signaling circuits are as follows: For the vertical impulse signals the circuit is from grounded terminal G (Fig. 2), thence to and through terminal G the pair of contact springs shown immediately above the signal transmitter, which springs are closed as soon as the dial is moved from its normal position the middle spring of the impulse springs, thence, when the signal transmitter is operated, to the upper or vertical impulse spring, the terminals V V lefthand contacts of relay 19, terminal V. conductor V at station Y (Fig. 1), to and through the contacts of key YT, the upper heavy line or vertical side of the trunk to the central oflice, thence throughthe vertical stepping means at the central oflice to the ungrounded pole of the central office battery.

The circuit for the rotary impulse is as follows: from ground (Fig. 2), through terminals G G to and through the pair of contact springs immediately above the signal transmitter, thence to the middle impulse spring, lower impulse spring to the terminals R R through the right hand an mature and contact of relay 19 to terminal. It, thence to conductor R, station Y (Fig. 1), to and through the lower pair of contact springs of key YT, to the lower heavy line or rotary side of the trunk line, the left hand contacts of relay. 9, to the rotary side of the trunk line extending to the central oflice, thence through the rotary stepping means at the central office to the ungrounded pole of the central ofiice battery. The operation of the dial of the calling stat-ion whose equipmentis shown in Fig. 2 changes the position of the switching element 12, the switch element 12 then remaining in contact with its right hand element until the depression of the hooki lever. This offers a path from the negative side of the ringing battery RB of Fig. 2 through terminals E -B conductors 13, 141-, switch element 12, conductors 15 to terminal P of conductor 16 or guard conductor of the trunk, thence through relay 25 "to plus' side of battery RB, operating relay 25 and opening the ringer bridge of the trunk.

Should station Z attempt to call upon the trunk, his first act would be to depress his key ZT. This would give, a circuit beginning at the negative side of ringing battery and extending through terminals 13 -13 of station Y'thence through 13, 14, 15, P, YT, 16, to station Z, thence through key ZT, terminal P of station Z, conductor 15, switch element 12, and its left hand contact element, conductor '17 of station Z to and through closed contact of hook switch when elevated, conductor 18, helix of relay 19, to positive side of ringing battery which is common to all stations, thus energizing relay 19 and accomplishing two results. The first result is the breaking of the conducting'paths be-- tween VI-V, and B -R, the terminals V} and B being connected to the trunk condu'ctors at the key ZT,.and the telephone set being removed therefrom by the operation or" the relay 19. The further result is the clos-Q ing of a local circuit extending from nega tive side of ringing battery RB toterminal B to and through armature 19 and its contact, through buzzer 20'and to terminal B which is the positive terminal of RB. This 1 ing patron that the trunk line is busy. It is 7 not the intention of the system of my invention to lock out the private branch station from'thetrunk conductors positively, but only to protect the user of the trunk conductors against unintentional interruption.

If the patron at station Z, learning that the trunk line is busy, still desiresto connect his telephone with the trunk line, he may do .so

by giving one pull upon his transmitting dial, thereby operating his switch element 12, removing the relay 19 from its connection with the wire 16, the relay 19 thereby releasing its armature and placing the telephone set of station Z in connection with the trunk conductors. V

On an incoming connection where the private branch exchange patron isthe called party to the conversation, the dial at the private branch exchange is not operated and switch element 12 is not shifted. For this reason the guarding condition is not laced upon the guard wire 16, and any number of stations may come'upon the line intentionally or otherwise. This is necessary in order that the desired party to an incoming'call may be permitted to have access to the trunk to answer the call, but the guarding condition may be placed upon the guard wire16 at any time by any station merely by giv the switch element .12. l

WVhen a local station as station Ycalls an 1 other local station as station-Z, the call is elfectedby depressing the key 3 fully to close its contact 3 and then releasing to its* locking or intermediate position. During the complete depression of the key B as suming that station Z is in idleness, a circuit will be formed extending from the plus side" of the common ringing battery RB Fig. 2 over the bus wire of'the system to terminal B thence'through ringing buzzer 20 to ter-- minal RB of Fig. 2, which is connected to conductor RBof ig. 1 and to contact 3 of key 3 then to one of the wires of the line upon which it'is desired to ring and over that wire to station Z, thence over wire C Fig. 1 at station Z to-terminal C of Fig 2 through the vibrating call bell 22 of station Z through terminals C C and closed contact pair of hook switch, terminals 13 -13 and bus wire to minus side of the ringing battery. Current flowing over this circuit 1 Wlll operate the callbell 22' of station Z and the ringing buzzer 20 of station Y, an-y nounc ng to station Y' that the callbell at station Z is being actuated. If, however, the

hook at station Z were elevated, the contact of thefhook switch included'in the circuit would bebroken and neither the call hell I of the desired station nor the buzzer-of the originating. station would belf actuate' d, thus giving a negative signal to the originating I 7 1 station, indicatlng the busy condition of the desired'station. Thecalled'subscriber at Z answers by depressing the key corresponding to [his own station. In the receiving station the hook switch contact of the above circuit is replaced by the conductor 24. An,- exception is made at the receiving station,

its circuit being so arranged as tofpermit its bellto be rung at any time in order that thereceiving station may be called while handling incoming calls or otherbusinessf 1 In incoming calls from the central office, the call is answered regularly atthe receiv ing station, theringer 10 being located at that station, andithe ringing current from the central office coming infrom the right along the heavy lines as viewed in Fig. 1 and and learns the identity ofthe station desired. The act of answering by depression ofthe key XT placesthe attendants telephone across the telephone pair in series with the windings of relay 9, thus energiz I ing that relay and closing-a bridge path across the pair composed ofone winding of the relay 9, an armature and contact of the same relay, and the ringer 10, the relay Winding involvedL being shunted by a condenser 23. The circuits established when the attendant operates the key VXT are as follows: from the ungrounded pole of the central ofli'ce battery over the upper or vertical side of the trunk line (Fig. 1), through the contacts of key XT, thence to conductor V, terminal V (Fig. 3), left hand armature and contact of relay 19, terminal V -V to and through upper pair of hook-switch contacts of the subscribers station instrument (which contacts are closed when the receiver is removed from the hook), thence through the transmitter, primary winding of the induction coil, terminals R R right hand armature and contact of relay 19 to terminal R, thence by conductor B (Fig. 1, station X) to lower set of contacts of key XT, thence to and through the two windings of relay 9 in parallel to the lower or rotary side of the trunk line, thence over this trunk conductor to the grounded pole of the central ofiice battery.

The circuit just described includes the windings of relay9 in parallel, which will cause this relay to operate. The circuit conditions after the operation of relay 9' are as follows: The circuit, as previously described,

remains the same to the lower set ofcontacts of the key XT (Fig. 1). It then extends to and through'right hand winding of relay 9, thence by the rotary trunk conductor to the central office. tablishes a bridge'path across ,the'vertical and rotary conductors of the trunk line as follows: from the vertical side of the trunk line to and through contact and armature call the local station desired, the signals or' relays at the central office being held in proper condition of controlby the trunk bridge composed'of the relay winding and the ringer 10. The attendant at the receiving station notifies the party at the desired station, and the desired party now depresses the proper trunk button at his station Y or Z. This act, in addition to picking up the trunk, automatically removes the bridge at the receiving station since the current taken by the desired station at key YT or ZT is taken through both of the differential windings of relay 9 in series, thus demagnetizing the relay and releasing its armature and short circuiting the windings. The central office devices are now fully under the control of the bridge at the desired station and he may place a guard upon the trunk by pulling his dial once.

The attendant is notified that the desired patron has picked up the trunk in the fol- The operation of relay 9 eslowing manner: So long as he has not picked up the trunk, the relay 9 will remain energized and a path will extend from the minus side of ringing battery RB, see Fig. 1, through armature and contact of relay 9, thence through resistance 9, conductor T to terminal T of Fig. 3, terminal C and to and upon switch spring of the hook switch of the receiving telephonev set. If the attendant hang up the receiver before the desired party picks up the trunk, this path will be extended farther through the hook switch and through terminals B and RB, and ringing buzzer 20, to terminal B completing the circuit, and operating the buzzer 20, thus announcing to the attendant that the trunk has not been picked up by the desired party. This does not operate the relay 25 to break the bridge of the ringer 10.

The horizontal arrow to the left of the resistance 9 is a contact on a relay 9 associated with-another trunk when more than one trunk is employed.

I claim- 1. in a telephone system, a pair of speech current conductors, a guard wire associated therewith, a telephone set, an audible signal device, a relay therefor, a source of current; means in said telephone set for closing a path from said guard wire through said relay to one terminal of said source of current upon the initiation of a call, and further means for interrupting said path and for substituting therefor a path from said guard wire to the other side of said source of current and not including said relay.

2. In a telephone system, a pair of speech current conductors, a guard wire associated therewith, a telephone set, an audible signal device, a relay therefor, a source of current and means in said telephone set for closing a path from said guard wire through said relay to one terminal of said source of current upon the initiation of a call; further means for interrupting said path and for substituting therefor a path from said guard wire to the other side of said source of current and not including said relay, said further means being associated with automatic call sending devices of the telephone set and operated incidentally to the prosecution of the call. 7

3. In a telephone system, a pair of speech current conductors, a guard wire associated therewith, a telephone set, a telephone disabling relay; a source of current; means in said telephone set for closing a path from said guard wire through said telephone disabling relay to one terminal of said source of current upon the initiation of a call; and further means for interrupting said path and for substituting therefor a path from said guard wire to the other side of said source of current and not including said telephone disabling relay.

4. In. a telephone system, a pair'of speech current conductors, a guard wire. associated therewitlnian automatic telephone set, a relay for disconnectin said telephone set from said pair; a source of current; means in said telephone set for closing a path from said guard wire through said relay to one terniinalof said source of current upon the initiation of, a call, further means for interrupting said pathand for substituting therefor a path to the other terminal of said source of current and not including said rclay, said further means being associated withthe automatic call sending devices of the, telephone set and operated incidentally tovthe prosecution of the call.

7 5; In artelephone system, a pair of speech.

current conductors, a guard wire associated with said pair, a telephone set,'a busy test attery'normally not in operative relation: to said guard wire, an audible signal controlling relay, a hookswitch contact for placing said relay between said guard wire and one side of said busy test battery, thereby forming a busy test path, and a switch for removing said testpath and' for con-j necting said guard wire to the otherlterminal of said battery. I

6. In a telephone system, a pair of speech current conductors, a guard wire associated with'said pair, a telephone set, a busy test battery normally not in operative relation to said guard wire, automatic means for placing a telephone disabling relay between said guard wire and one side of said busy test battery to protect against interference with other telephone sets.

7. In a telephone system, a pair of speech current conductors, a guard wire associated with said pair, a telephone set, a relay for disconnecting said telephone set from said pair; a busy test battery normally not in operative relation to said guard wire, automatic means for connecting said relay between said guard wire and one side of said busy test battery to protect against interference with other telephone sets, and manually operated means for disrupting said connection.

I S. In a telephone system, a pair of speech current conductors, a guard wire associated with said pair, an automatic telephone set, a relay for disconnecting said telephone set from its line conductors, a busy test battery normally disconnected from said guard wire, hook switch contacts for connecting said relay between said guard wire and one side of said busy test battery to protect against interference with other telephone sets, and a switch for disrupting said connection and for connecting said guard wire to the other side of said battery, said switch being operated by a movement of the automatic calling devices of the telephone set.

9. In a telephone system, a relay having two windings;ia pair of speech current conductors in one of which'lthewindings ofsaid relay are included, serially and differentially; contacts on said-relay and short-cirings inductively toactuate said relay initially;. and a circuit controlled by another telephone set for passing current through lease said relay. 1-

10., In a telephone system, a relayhaving both of said windings differentiallyfto re-' two windings; a pair of speech current conductors in one of which the windings of said relay are included, seriallyand difierentially; contacts on said relay and connecting one of said windings in a path across said pair when in actuated position; a circuit controlled by a receiving telephone set andv actuating said relay initially; and a circuit controlledby another telephone set for pass ing current through both of said windings differentially to release said relay.

11. In a telephone system, a relay having two'windings; a pair of speech current conductors in one of'which the windings of said relay are included, serially and difl'erenti-..

ally; contacts on saidrelay and short-circuiting said windings when in normal position; contacts on said relay and connecting one of said windings in a path; across said pair when in actuated pos1tion;- a circuit controlled by a receiving telephone set and actuating said relay initially, and a circuit controlled by another telephone set and releasing saidlrelay.

12. In a telephone system, a plurality of automatic telephone instruments, a trunk circuit extending from said instruments to an automatic central ofiice, a plurality of local intercommunicatingcircuits between said instruments, means at each instrument for connecting with sai'd'trunk or local intercommunicatmg c1rcu1ts,and an automatic guard for said trunk circuit made operatlve when any one of'saidinstruments is connected therewithi: r

13. In a telephone system, a plurality of automatic telephone instruments, a plurality of trunk circuits extending from said instruments .to an automatic central oflice, a plurality of local intercommunicating circuits between said instruments, means at each in strument for selectively connecting with either of said trunk or local circuits, and an automatic guard for each of said trunk circuits made operative'when any one of said instruments is connected therewith. 14:. Ina telephone system, a plurality of telephone instruments, a trunk circuit extending from said instruments to an automatic central oilice, automatic sending devices associated with each of said instrumentsfor establishing connection over said trunk line through said central o'llice, a plurality of local circuits for intercommunication between said instruments, means at each instrument for connecting it With said trunk or local intercommunicating circuits, and an automatic guard for said trunk circuit made effective When one of said instruments is connected to said trunk circuit.

- devices for each of said instruments, a plu- Gopiesof this patent may be obtained for five rality of local circuits for intercommunicating between said instruments, means at each instrument for connecting it With said trunk or local intercommunicating circuits, and means Wherebythe user of one of said instruments Who has responded to a call over said trunk may arbitrarily place a guarding condition upon said trunk to prevent access of other stations to that trunk.

Signed by me at San Francisco, county of San Francisco and State of California, in the presence of two Witnesses.

' GERALD DEAKIN.

Witnesses:

R. H. GERARD, F. M. Comm.

cents each, by addressing the Commissioner of Patents,

Washington D. G. 

